A FAMILY OF THREE-LEVEL DC-DC CONVERTERS

Transcription

1 A FAMIY OF THREE-EVE DC-DC CONVERTERS Anonio José Beno Boion, Ivo Barbi Federal Universiy of Sana Caarina - UFSC, Power Elecronics Insiue - INEP PO box 5119, ZIP code , Florianópolis, SC, BRAZI ajbboion@gmail.com, ivobarbi@inep.ufsc.br Absrac This paper presens he sudy of a non isolaed family of dc-dc hree-level converers generaed from a commuaion cell wih wo diodes, wo acive power swiches and one inducor. Wih he proposed commuaion cell, he basic dc-dc converer opologies, namely, Buck, Boos and Buck-Boos are obained. Principle of operaion, mahemaical analysis, and design example are included in he paper, along wih experimenal resuls aken from a laboraory prooype raed in 500 W and 50 khz. I is demonsraed ha he proposed converer family subjecs he acive power swiches o lower volage, in comparison wih he convenional dc-dc non isolaed converers, as prediced by analysis. B A C Keywords Non isolaed, dc-dc converers, hree-level. Fig. 1: Three-level commuaion cell. I. INTRODUCTION A family of converers presened in [1] has a basic cell similar o ha presened in his work, bu he componens in differen posiion makes he cell in [1] unable o provide volage reducion on he swich, resuling in differen operaion for he respecive converers. In order o reduce he volage swich sress of convenional dc-dc non isolaed converers many sudies have been developed abou hree-level opologies. A sudy of a boos hree-level opology is presened in [2]. A buck hree-level opology sudy is showed in [3]. A discussion abou hree-level dc-dc converers employing ohers opologies and modulaion echnics is presened in [4]. This work is presened in is enirey in [5]. The commuaion cell proposed o reduce he volage sress across he power acive swiches is presened in Fig. 1. Wih his commuaion cell and a proper modulaion, he power acive swiches are subjeced o lower volage when compared wih he convenional dc-dc non isolaed converers sudied in [6]. The basic non isolaed hree-level Buck, Boos and Buck- Boos opologies are generaed from he commuaion cell in Fig. 1 connecing properly he source and he load in A, B and C erminals. To command he swiches and in Fig. 1 was proposed he PWM modulaion wih cenered pulses as shown in Fig. 2. To make sure ha he pulses in Fig. 2 are cenered is necessary ha Δ 3 =Δ 4. From Fig. 2 are defined ha =Δ 1 /T, =Δ 2 /T and D 5 = Δ 5 /T. Is also defined ha α = / and 0 α<1. Then 0 1 and 0 <. From bellow definiions is obained (1) and (2). D 5 =1 (1) = α. (2) Δ 3 Δ 1 Δ 4 Δ 2 T Δ Fig. 2: Cenered PWM pulses o command and. The Fig. 3 shows he relaionship among and parameers ploed from (2). In he nex secions are presened he non isolaed hreelevel opologies Buck, Boos an Buck-Boos o deal wih operaion sages, saic gain, curren inducor ripple and experimenal resuls. II. NON ISOATED DC-DC THREE-EVE BUCK CONVERTER A. Topology The non isolaed dc-dc hree-level Buck opology is shown in Fig. 4. Considering he opology in Fig. 4, he modulaion shown in Fig. 2 makes V S1 and V S2 lower levels han /13/$ IEEE 115

2 D α = 0.2 α = 0.4 α = 0.6 α = 0.8 α = Fig. 3: Relaionship among and for each fixed α value. V D2 i V S1 V S2 V V D1 Sage 1 [ 0, 1 ] [Refer Fig. 5(a)]: A 0 he swich is urned on and i say in branch... The volage across is. This sage ends when swich is urned on a 1. Sage 2 [ 1, 2 ] [Refer Fig. 5(b)]: A 1 he swich is urned on and i increases linearly wih ( )/ rae. This sage ends when is urned off a 2. Sage 3 [ 2, 3 ] [Refer Fig. 5(c)]: A 2 he swich is urned off and i say in branch.. again. The volage across is like he sage 1. This sage ends when swich is urned off a 3. Sage 4 [ 3, 4 ] [Refer Fig. 5(d)]: A 3 he swich is urned off and boh swiches are off. The diode conducs and i decreases linearly wih / rae. The volage on he swich remains, so he volage a swich is equal o. This volage disribuion in he swiches depends on is drain-source off-resisance and is inrinsic drain-source capaciors. This sage ends when swich is urned on a 4 saring a new operaion period. C. Principal Waveforms The principal waveforms considering operaion on coninuous conducion mode (CCM) are shown in Fig. 6. In his figure is clear ha he maximum volage across each acive swich is always lower han inpu volage, ha is he highes volage involved in conversion. Fig. 4: Non isolaed dc-dc hree levels Buck opology converer. B. Operaion Sages The non isolaed dc-dc hree-level Buck converer has four operaion sages considering operaion in coninuous conducion mode (CCM) as shown in Fig. 5. -Vo i -Vo i Vo i v S1 - i S1 v S2 i S2 (a) (b) i i -Vo -Vo Vo Vo (c) i Fig. 5: Operaion sages in coninuous conducion mode (CCM). (d) 0V i Fig. 6: Principal waveforms considering operaion on coninuous conducion mode (CCM). 116

3 D. Volage saic gain From mahemaical analysis, considering operaion on coninuous conducion mode (CCM), he volage saic gain is given by (3) as a funcion of and by (4) as a funcion of. q = α. = (3) α.( +1) q = α. = 1+.(α 1) (4) The volage saic gain on disconinuous conducion mode (DCM), is given by (5) as a funcion of. q = =1.(1 ) f E. Inducor ripple From heoreical analysis considering operaion on coninuous conducion mode (CCM) he lowes ( ) and he highes ( ) curren levels on inducor is given by (6) and (7) respecively. (5) Fig. 7: Three-level Buck exernal characerisic. = = Where: - oad curren. f - Swiching frequency..(1 ) f +.(1 ) f (6) (7) F. Exernal Characerisic In order o plo he hree-level Buck exernal characerisic he load curren was parameerized as given by (8). Fig. 8: Volage waveform on swiches and. = 2...f (8) The Fig. 7 shows hree-level Buck exernal characerisic for α =1, α =0.8, α =0.6 and α =0.4. G. Experimenal resuls The specificaions for a prooype projec are presened in Tab. I. TABE I: Buck specificaions Parameer Value Uni 300 V 200 V P o 500 W f 50 khz α 0.7 Fig. 8 shows he volage waveform on swiches and. In Fig. 9 are shown he inpu volage and oupu volage waveform. Fig. 9: Inpu volage and oupu volage waveform. 117

4 III. NON ISOATED DC-DC THREE-EVE BOOST CONVERTER A. Topology The opology of non isolaed dc-dc hree-level Boos converer is shown in Fig. 10. V V D2 i V S2 V S1 V D1 Fig. 10: Non isolaed dc-dc hree-level Boos converer opology. across is like he sage 1. This sage ends when swich is urned off a 3. Sage 4 [ 3, 4 ] [Refer Fig. 11(d)]: A 3 he swich is urned off and boh swiches are off. The diode conducs and i decreases linearly wih ( )/ rae. The volage on he swich remains, so he volage a swich is equal o. This volage disribuion in he swiches depends on is drain-source off-resisance and is inrinsic drain-source capaciors. This sage ends when swich is urned on a 4 saring a new operaion period. C. Principal Waveforms The principal waveforms for operaion in coninuous conducion mode (CCM) are shown in Fig. 12. In his figure is clear ha he maximum volage across each acive swich is always lower han oupu volage, ha is he highes volage involved in conversion. i Considering he opology in Fig. 10, he modulaion shown in Fig. 2 makes V S1 and V S2 lower levels han. B. Operaion Sages Considering operaion on coninuous conducion mode (CCM), he non isolaed dc-dc hree-level Boos converer has four operaion sages as shown in Fig. 11. v S1 i S1 v S2 - i Vo- i Vo- i S2 (a) (b) i i i (c) Vo- i D 2 0V (d) Vo- Fig. 11: Operaion sages on coninuous conducion mode (CCM) Fig. 12: Principal waveforms for operaion on coninuous conducion mode (CCM). Sage 1 [ 0, 1 ] [Refer Fig. 11(a)]: A 0 he swich is urned on and i say in branch... The volage across is. This sage ends when swich is urned on a 1. Sage 2 [ 1, 2 ] [Refer Fig. 11(b)]: A 1 he swich is urned on and i increases linearly wih / rae. This sage ends when is urned off a 2. Sage 3 [ 2, 3 ] [Refer Fig. 11(c)]: A 2 he swich is urned off and i say in branch.. again. The volage D. Volage saic gain From mahemaical analysis, considering operaion on coninuous conducion mode (CCM), he volage saic gain is given by (9) as a funcion of and by (10) as a funcion of. = α +.(α 1) (9) α 118

5 = 1+.(α 1) 1 (10) The volage saic gain on disconinuous conducion mode (DCM), is given by (11) as a funcion of. q = =1+.( ) f (11) TABE II: Boos specificaions Parameer Value Uni 300 V 500 V P o 500 W f 50 khz α 0.77 E. Inducor ripple From heoreical analysis, considering operaion in coninuous conducion mode (CCM), he lowes and he highes curren levels on inducor is given by (12) and (13) respecively. = = f f (12) (13) F. Exernal Characerisic In order o plo he hree-level Boos exernal characerisic he load curren was parameerized as given by (14). = 2...f (14) The Fig. 13 shows hree-level Boos exernal characerisic for α =1, α =0.8, α =0.6 and α =0.4. Fig. 14: Volage waveform on swiches and. Fig. 15: Inpu volage and oupu volage waveform. Fig. 13: Three-level Boos exernal characerisic. G. Experimenal resuls The specificaions for a prooype projec are presened in Tab. II. Fig. 14 shows he volage waveform on swiches and. In Fig. 15 are shown he inpu volage and oupu volage waveform. IV. NON ISOATED DC-DC THREE-EVE BUCK-BOOST CONVERTER A. Topology The opology of non isolaed dc-dc hree-level Buck-Boos converer is shown in Fig. 16. Considering he opology in Fig. 16, he modulaion shown in Fig. 2 makes V S1 and V S2 lower levels han +. B. Operaion Sages Considering operaion on coninuous conducion mode (CCM), he non isolaed dc-dc hree-level Buck-Boos converer has four operaion sages as shown in Fig

6 V S1 V S2 V D1 i V D2 V v S1 i i S1 Fig. 16: Non isolaed dc-dc hree-level Buck-Boos converer opology. v S2 i i + i S2 (a) (b) i i i (c) Fig. 17: Operaion sages on coninuous conducion mode (CCM). Sage 1 [ 0, 1 ] [Refer Fig. 17(a)]: A 0 he swich is urned on and i say in branch... The volage across is. This sage ends when swich is urned on a 1. Sage 2 [ 1, 2 ] [Refer Fig. 17(b)]: A 1 he swich is urned on and i increases linearly wih / rae. This sage ends when is urned off a 2. Sage 3 [ 2, 3 ] [Refer Fig. 17(c)]: A 2 he swich is urned off and i say in branch.. again. The volage across is like he sage 1. This sage ends when swich is urned off a 3. Sage 4 [ 3, 4 ] [Refer Fig. 17(d)]: A 3 he swich is urned off and boh swiches are off. The diode conducs and i decreases linearly wih / rae. The volage on he swich remains, so he volage a swich is equal o. This volage disribuion in he swiches depends on is drain-source off-resisance and is inrinsic drain-source capaciors. This sage ends when swich is urned on a 4 saring a new operaion period. C. Principal Waveforms The principal waveforms considering operaion on coninuous conducion mode (CCM) are shown in Fig. 18. In his figure is clear ha he maximum volage across each swich is always lower han he sum he inpu and oupu volage. D. Volage saic gain From mahemaical analysis, considering operaion on coninuous conducion mode (CCM), he volage saic gain is given by (15) as a funcion of and by (16) as a funcion of. 0V (d) i Fig. 18: Principal waveforms for operaion on coninuous conducion mode (CCM). = α. α (15) = α. 1 (16) The volage saic gain on disconinuous conducion mode (DCM), is given by (17). q = =. R o 2..f = α.. R o 2..f (17) E. Inducor ripple From heoreical analysis, considering operaion on coninuous conducion mode (CCM) he lowes and he highes curren levels on inducor is given by (18) and (19) respecively. = = f f (18) (19) 120

7 F. Exernal Characerisic In order o plo he hree-level Buck-Boos exernal characerisic he load resisor was parameerized as given by (20). R o R o = (20) 2..f The Fig. 19 shows hree-level Buck-Boos exernal characerisic for α =1, α =0.8, α =0.6 and α =0.4. Fig. 20: Volage waveform on swiches and. Fig. 19: Three-level Buck-Boos exernal characerisic. G. Experimenal resuls The specificaions for a prooype projec are presened in Tab. III. Fig. 21: Inpu volage and oupu volage waveform. TABE III: Buck-Boos specificaions Parameer Value Uni 300 V 300 V P o 500 W f 50 khz α 0.8 Fig. 20 shows he volage waveform on swiches and. In Fig. 21 is shown he inpu volage and oupu volage waveform. V. CONCUSION From he heoreical and experimenal sudies presened in he paper, we can draw he conclusions as follows. 1) The power semiconducor are subjeced o lower volages, in comparison wih he convenional wo level dc-dc converers; 2) In opposiion o he convenional converer, he new converer family has wo inpu variables, ha can be use no only o conrol he power ransferred o he load, bu also o improve saic and dynamic performance of he converers; 3) The operaion and he quaniaive analysis resuls have been validaed in he laboraory; 4) I is he auhor s opinion ha he proposed converer family is appropriae o subsiue he convenional non isolaed dc-dc converers in applicaions where he volages exceed he raed volage of commercial power swiches, in low and medium power. REFERENCES [1] C. A. Bissochi Jr., F. R. S. cenzi, V. J. Farias, J. B. eira Jr., and. C. Freias, Uma nova família de conversores eie, in Congresso Brasileiro de Auomáica, 2002, pp [2] K. swanahan, R. Orugani, and D. Srinivasan, A novel ri-sae boos converer wih fas dynamics, IEEE Transacions on Power Elecronics, vol. 17, no. 5, pp ,

8 [3] V. Yousefzadeh, E. Alarcon, and D. Maksimovic, Threelevel buck converer for envelope racking applicaions, IEEE Transacions on Power Elecronics, vol. 21, no. 2, pp , [4] X. Ruan, B. i, Q. Chen, S.-C. Tan, and C. Tse, Fundamenal consideraions of hree-level dc-dc converers: Topologies, analyses, and conrol, IEEE Transacions on Circuis and Sysems I: Regular Papers, vol. 55, no. 11, pp , [5] A. Boion, Conversores cc-cc básicos não isolados de rês níveis, Maser s hesis, Federal Universiy of Sana Caarina, [Online]. Available: hp:// boion.pdf [6] I. Barbi and D. C. Marins, Conversores CC-CC básicos não isolados. Auhors ediion,